1. Technical Field
The present invention relates to an air suction device for a toilet drain passage.
2. Related Art
FIG. 7 of Japanese Patent Application Publication JP-A-H05-311719 discloses a conventional air suction device for a toilet drain passage. The air suction device has a suction tank and a hydraulic drive unit, so that air is sucked from a toilet drain passage continuing to the downstream side of a water sealing section of toilet body.
The suction tank is provided with a first diaphragm movable in a vertical direction defined at the time of installation in a housing and is partitioned into an upper first chamber and a lower second chamber by the first diaphragm. The second chamber of the suction tank communicates with the toilet drain passage. The hydraulic drive unit has a second diaphragm to which tap water is supplied through a water conduit so that the second diaphragm is moved upward, and a bar-like member which is mounted on an upper surface of the second diaphragm and has a distal end connected to the first diaphragm.
In the suction device, tap water is supplied to the hydraulic drive device upon start of toilet flushing so that the second diaphragm is moved upward. Then the bar-like member drives the first diaphragm upward such that air in the toilet drain passage is sucked into the second chamber of the suction tank. As a result, since flush water is caused to flush into the toilet drain passage swiftly, a strong siphon action can be initiated at an early stage. Consequently, the siphon action can be initiated even by a smaller amount of flush water, and waste can be discharged out of the toilet body. Upon finish of the toilet flushing, tap water is discharged through the water conduit from the hydraulic drive unit, whereupon the first diaphragm is moved downward. As a result, the suction device can be prepared for next toilet flushing.
In the foregoing conventional suction device, however, the clogging of the water conduit results in an abnormal condition such as being unable to supply tap water into the hydraulic drive unit. When the second diaphragm is not moved upward, the first diaphragm cannot be moved upward such that an amount of air sucked from the toilet drain passage becomes insufficient. Since the siphon action cannot be initiated in this case, the toilet flushing would not be performed suitably. Furthermore, when tap water is not completely discharged out of the hydraulic drive unit, the first diaphragm is stopped during the downward movement thereof. In this case, an amount of air to be sucked from the toilet drain passage for the next toilet flushing is decreased, whereupon there is a possibility that the toilet flushing cannot be performed suitably without initiation of a siphon action.
Furthermore, an amount of tap water supplied per time or the like changes with a change in an installation location such as an area, building, floor, etc. where the toilet body is installed, and status of use such as a time zone when the toilet body is used, and the like. This then changes a speed at which the second diaphragm is upwardly moved and an amount of upward movement of the second diaphragm, resulting in changes in a speed at which the bar-like member pushes the first diaphragm upward, and the like. This results in variations in status of suction of air in the toilet drain passage by the second chamber, whereupon the toilet flushing may not be carried out successfully.
More specifically, when the speed at which the first diaphragm is pushed upward is excessively high, air is sucked by the second chamber from the toilet drain passage under the condition that flush water is not sufficiently supplied into the toilet body. In this case, the siphon action may not be initiated since a sufficient amount of flush water cannot be caused to flow into the toilet drain passage. Furthermore, when the speed at which the first diaphragm is pushed upward is too low or when an amount of movement of the first diaphragm is too small, an air suction force of the second diaphragm from the toilet drain passage is reduced. In this case, too, the siphon action may not be initiated since a sufficient amount of flush water cannot be caused to flow into the toilet drain passage. When no siphon action is initiated, waste is not discharged outside the toilet body, whereupon the toilet flushing may not be carried out successfully.